First- and Second-Order Models of Recursive Arithmetics

Ján Kľuka, Paul J. Voda

We study a quadruple of interrelated subexponential subsystems of arithmetic WKL${}_0^{-}$, RCA${}_0^{-}$, I${\Delta }_0$, and $\Delta$RA${}_1$, which complement the similarly related quadruple WKL${}_0$,…